Those of ordinary skill in the art will appreciate that the oil industry often uses three-dimensional (3D) visualization to showcase its exploitation of the latest high-tech developments. (As used herein, the term “visualization” is intended to encompass a process involving the computer processing, transformation, and visual/graphical display of measured or simulated data to facilitate its interpretation.) Visualization has become a well-established planning and analytical tool for the geological and geophysical (G&G) segment of the industry. Benefits extend beyond technical issues, as communal visualization has promoted multi-disciplinary discussion and created opportunities to bring people together and improve the dynamics of E&P teams by providing clarity in the face of the ever increasing amount of data that forms the modern well construction process.
Similar success is being achieved in drilling. Early applications focused on well placement in complex reservoirs, and directional drilling to control well tortuosity and avoid collisions on multi-well platforms. More recent applications use 3D visualization to address drilling problems and link drilling operational data to earth models. Countless other drilling prospects should exist, especially considering that “making hole” occurs out of sight, miles below the earth's surface.
In the prior art, downhole visualization has focused principally on the trajectory of the borehole, particularly with the ever-increasing popularity of directional drilling. Knowing the precise location of the borehole at all points along its length is critical to ensure that the drilling operation succeeds ultimately in the borehole arriving at the desired production region.
Downhole video is a proven telepositioning method for mechanical inspection, fishing operations, and problem investigation in a wellbore. Unfortunately, downhole video cannot be used during drilling, because (a) nearly all drilling fluids are opaque; (b) normal drilling operations would have to be suspended; and (c) the drill string would interfere with camera operations.
Videos taken of simulated wellbores in the laboratory, despite temperature and pressure shortcomings, have contributed significantly to the industry's understanding of downhole behavior, especially hole cleaning and barite sag. Remarkable footage captured through transparent, inclined flow loops have documented the impact of different parameters on hole-cleaning efficiency, including hole angle, annular velocity, pipe eccentricity and rotation, low-shear-rate viscosity, flow regime, and avalanching cuttings beds. Video has also helped validate the field success with drilling horizontal wells at some sites with rheologically engineered bio-polymer drill-in fluids, a hole-cleaning concept that was contrary to industry thinking at the time. Additionally, laboratory studies based on extensive video imaging helped convince the industry that barite sag was primarily a dynamic settling problem and not the static problem as previously thought.
Nevertheless, video examination of actual wellbores is not a practical alternative, meaning that other means must be employed to analyze dynamic parameters of the interior of a wellbore.
Outside of the oil industry, video has long been a mainstay to view objects not easily accessible. The medical field is perhaps the best known, and the colonoscopy is an excellent analogy to downhole video technology. Recent technological advancements have made it possible to perform a non-invasive procedure called a “virtual” colonoscopy. The virtual colonoscopy process involves performing a spiral (or helical) computer-aided tomography (CAT) scan, wherein a rotating x-ray machine follows a spiral path around the body. A high-powered computer uses the x-ray data to create detailed cross-sectional pictures of the body. The high-resolution, 2D pictures are then assembled like slices in a loaf of bread to construct a detailed, 3D image of the colon lining suitable for thorough analysis by the doctor.
Virtual images created for medical use invariably are based on measured data. Unfortunately, detailed data required along a well path cannot be measured with current technology. The alternative is to simulate the downhole drilling process with appropriate models. Logically, the accuracy of the models is important.
To address this problem, computer applications have been developed for simulating the internal environmental dynamics within wellbores based on known or modeled data about the well. Advanced software has emerged that considers, among other things, the effects of temperature and pressure on density and rheology. Numerous commercially-available examples of such analysis applications are known in the art. An interesting aspect of such programs is that the modules created for calculating equivalent static densities (ESDs) are based on numerical integration of short wellbore segments. This approach has set the stage for using techniques involving finite difference analysis for other calculations. Generally speaking, hydraulics applications function to take a number of dynamic, depth-varying parameters for a wellbore (and drillstring) as inputs to provide as an output one or more indicators of well performance and behavior.
Accuracy is a serious issue regarding downhole simulation. Often measured data or a combination of simulated and measured data can be used simulating the internal environmental dynamics within wellbores. Currently much of this data is presented in traditional two dimensional graphs or in data tables. However, in many cases, large datasets make this cumbersome or mentally impossible. Thus there remains an on-going need for methods of viewing and analyzing the data sets in a mentally appealing manner.